In recent years, the number of speakers who make a remote conversation by using a transmission terminal such as a PC (Personal Computer) or a cellular phone is drastically increasing. Not only a conversation between two points (two persons), but a conversation among multiple points (three or more persons) can also be made.
Additionally, an administrator who runs a communication service for a conversation between transmission terminals obtains profits by charging users of transmission terminals of a communication fee. As a method for charging such a communication fee, there is disclosed a method for equally charging speakers (participants) who take part in a conversation of a fee for communication from the start to the end of the conversation (see Japanese Patent Application Laid-open No. 09-172509).
However, for example, another speaker may take part in a conversation using another transmission terminal during the conversation between two points, or a speaker using a given transmission terminal used for the conversation may leave the conversation during the conversation among multiple points. In such cases, there is a problem that the speaker is charged with a same fee of communication from the start to the end of the conversation even though the speaker did not take part in the actual conversation. This causes the inequality in charged fee.